A graded-index plastic optical fiber (GI POF) with a high bandwidth and flexibility is expected to be a transmission medium for short-reach communication in home networks. However, the pluggable interconnects for consumers have not been emerged. Recently, we have developed ballpoint-pen interconnects where ball lens can be precisely mounted on GI POF end face using ballpoint-pen production technology, enabling easy connection, low-cost production, and fiber end face protection of GI POFs. Here, data transmission quality through coupled GI POFs with the ballpoint-pen connector is investigated. For evaluating data transmission quality, we measured bit error rate versus received optical power (BER curve) for a connector separation of 1.5 mm in the ballpoint-pen interconnect. The result shows error-free transmission (BER<10-12) was achieved by using the ballpoint-pen interconnect whereas transmission quality was significantly deteriorated by using the butt-coupling which is generally physically-contacted without fiber separations. This achievement with the ballpoint-pen interconnect may result from little dependence of the coupling loss on the connector separation because of the collimated output beam from GI POF with the ballpoint-pen connector. Furthermore, even for same received optical powers in the BER curve, the butt-coupling has worse transmission quality than the ballpoint-pen interconnect. This may result from some noises such as modal noise which occurs in multimode fiber connection as fluctuations of the coupling power. These results suggest that the ballpoint-pen interconnect is suitable for a consumer applications where the pluggable interconnects are essential. In the conference, the connector separation dependence of transmission quality through ballpoint-pen interconnect will be discussed.

Recently, ultra-high definition (UHD) displays have been rapidly developed for video formats with 4K (3840x2160) and 8K (7680x4320) resolutions. In Japan, 4K/8K broadcastings are scheduled to be started, accelerating research and development of 4K/8K distribution technologies. Current UHD displays require uncompressed video transmission with a bit rate well above 100 Gb/s, suggesting that extremely high bit-rates are required even at home in the upcoming 4K/8K era. Therefore, consumer-friendly pluggable optical interface has been highly demanded.
A graded-index plastic optical fiber (GI POF) has been has been a promising optical interface cable for the consumer applications because of its flexibility, safety, and high bandwidth, which allows for transmission speeds up to ~ 40 Gb/s through a 100-m GI POF. Recently, we demonstrated that GI POFs have noise reduction effects which are closely related to microscopic heterogeneities of the core material. Here, we propose a low-noise GI POF for uncompressed 8K video transmission based on noise-sensitive multilevel pulse amplitude modulation (PAM).
We evaluated worst-case bit-error-rate curve of for the low-noise GI POF and a silica GI MMF in the extremely-short optical link, where we used PAM-2 with the corresponding modulation voltage to minimum symbol-level difference in PAM-4. The results showed that the transmission quality is dominantly determined by not loss and bandwidth but noise and stability. Using the low-noise GI POF, we could significantly stabilized data transmission without precise alignment, angled fiber-facets, and optical isolators. The novel GI POF allows for consumer-friendly optical interface for the 8K video multilevel transmission. This research is based on results obtained from a project commissioned by the NEDO.

The growing demand for high-speed data transmission in consumer applications such as 4K/8K television motivates the development of multilevel modulation. Multilevel modulation can increase bit rate over 2-level modulation for same symbol rate, but is subject to noise and modulation instability in optical link. Recently, we experimentally demonstrated that a graded-index plastic optical fiber (GI POF) significantly improved the transmission signal quality compared with a silica GI multimode fiber (MMF) in the consumer-friendly MMF link without an optical isolator, where laser and optical fiber easily coupled. This high-quality transmission is related to reflection noise reduction because of a strong mode coupling in the GI POF. However, the signal quality also depends on the modulation response of the vertical-cavity surface-emitting laser (VCSEL) coupled with optical fibers. Here, we investigate the influence of the strong mode coupling in the low-noise GI POF on the modulation response of the VCSEL in the consumer-friendly MMF link. We show that the low-noise GI POF can significantly decrease the distortion of the modulation response compared with the silica GI MMF which easily coupled with the VCSEL. This low-distortion performance is related to the strong mode coupling in the low-noise GI POF, which stabilizes the VCSEL owing to the self-coupling reduction of the optical feedback into the VCSEL cavity. This suggests that the novel GI POF allows for highly-stabilized multilevel transmission for consumer-friendly 8K interface. In the conference, we will also discuss the mechanism for the stabilization effects of the low-noise GI POF using theoretical analyses.

Several kinds of optical polymer films in liquid crystal displays (LCDs) greatly contribute to image quality. However, contrast ratio of LCDs degrades with an increase in birefringence of polymer films used in the LCDs. The major types of birefringence are orientational birefringence and photoelastic birefringence. Furthermore, it was recently found that the birefringence caused by specified conformation and degree of orientation of polymer chains strongly depends on the temperature. We designed and synthesized a temperature-independent zero-birefringence polymer (TIZBP): poly(methyl methacrylate/benzyl methacrylate/phenyl methacrylate = 45/22/33(wt.%)) that has zero intrinsic birefringence over a wide temperature range in the random copolymerization method. However, the glass transition temperature Tg of this TIZBP is 95°C, and heat-drawn films of this TIZBP shrank at lower temperature than Tg, for example, at about 60°C. Upper limit of operating temperature of LCDs in automobile is higher than 60°C. Therefore, this TIZBP is not proper for practical use in automobile.
In this research, after analysis of heat shrinkage of heat-drawn films, heat-resistant TIZBP (HRTIZBP) that exhibits sufficiently low heat shrinkage at 60°C, zero intrinsic birefringence and zero temperature coefficient of intrinsic birefringence was designed and synthesized. First of all, heat shrinkage ratio of heat-drawn films of poly(methyl methacrylate)，poly(methyl methacrylate/benzyl methacrylate) and TIZBP was investigated. The heat shrinkage of polymer films began at Tg-55°C. Based on the results, because targeting Tg for HRTIZBP was determined to 125°C, higher than 115°C with a sufficient margin, poly(methyl methacrylate/phenyl methacrylate/N-ethyl maleimide = 39/45/16 (wt.%)) was synthesized. This polymer exhibits lower heat shrinkage than the existing polymers, especially the heat shrinkage at 60°C is 0.0%. Therefore, this polymer was confirmed to be HRTIZBP.

Along with the increase of the demand for Ultra-High-Definition (UHD) such as 8K, a tremendously large bit-rate data transmission will be required inside home and among consumer devices. For 8K video, a required transmission speeds will be up to 240 Gb/s. Conventional metal cables such as serial digital interfaces are not suitable for UHD application, because of increases in electric consumption and electro-magnetic interference. Therefore, the key is to implement optical fibers into every corner of homes and consumer devices. It means a paradigm-shift from electrical wire to optical fiber. Recently, we have a discovery that the novel graded-index plastic optical fiber (GI POF) with specified micro-heterogeneities in core of fiber dramatically reduces the modal noise, resulting in the stable data transmission without optical isolator and precise alignment. This novel GI POF is being paid a lot of attention to as one of the strongest candidates for supporting UHD displays and tablets especially in consumer photonics.
We have successfully proposed and developed both the new zero-birefringence polymer films and ultra-high birefringence polymer films towards real-color high-definition displays ahead of the world. The new zero-birefringence polymer exhibits always “zero-birefringence” for deformation of polymer chains, adding stress to polymer, and changing temperature. The ultra-high birefringence polymer films have been already commercially used in LCD TV, and have been developed for new type displays including both LED and OLED. These polymers eliminate the long-standing issue of birefringence which causes color irregularities, and realizes the extremely real color for ultra-high definition display.

Liquid crystal displays (LCDs) are composed of two glass substrates, two polarizers and some optical films. These components are laminated by pressure sensitive adhesives (PSAs). When a polarizer shrinks by humidity or the heat from a backlight of LCDs, stress appears and deforms PSAs. PSAs tend to exhibit birefringence due to applied stress and temperature change, which causes light leakage degrading image quality of LCDs. PSAs are consisted of main chain polymers and cross-linkers. To evaluate birefringence of PSAs at room temperature is difficult because PSAs easily plastically deform at the temperature. The purpose of this article is to design temperature-independent zero-birefringence PSAs (TIZBPSAs) exhibiting almost no birefringence even during stress-induced deformation over a wide temperature range. Butyl acrylate (BA) and phenoxyethyl acrylate (PHEA) were selected as the monomers of main chain polymers and an isocyanate-type cross-linker was added. Trilaminar films were prepared in which PSAs were sandwiched between two supporting films. We successfully evaluated birefringence and temperature dependence of birefringence of PSAs for the first time by using temperature-independent zero-birefringence polymers (TIZBPs) as the supporting films. TIZBPs, designed in our group, show almost no orientational birefringence even when the polymer main chain is in an oriented state and almost no temperature dependence of orientational birefringence over a wide temperature range. We have proposed a novel method to design PSAs having desirable the birefringence properties by determining the contributions of BA, PHEA and the cross-linker to birefringence and temperature dependence of PSAs quantitatively. Furthermore, we have designed TIZBPSAs by the proposed method.

Poly(pentafluorostyrene) (PPFS), which can be easily synthesized and has a low optical loss window at 850 nm, is a promising alternative for a costly perfluorinated polymer as a base material of polymer optical fibers (POFs). To investigate the potential of a PPFS-POF as a Brillouin-based temperature sensing fiber, the Brillouin frequency shift and its temperature dependence of PPFS were estimated using an ultrasonic pulse-echo technique. The temperature coefficient, which determines the sensitivity of the temperature sensing, was approximately –7.1 MHz/K independently of the molecular weight and was nearly identical to that in perfluorinated POFs.

In this work we perform a detailed experimental and theoretical analysis of the properties of amplified spontaneous
emission (ASE) in a rhodamine-6G-doped graded-index polymer optical fiber when the fiber is pumped either
longitudinally or transversally with respect to the fiber axis. The dependence of the ASE threshold and efficiency on
fiber length has been compared for both schemes of excitation. A theoretical model for longitudinal excitation has been
carried out by means of the laser rate equations as functions of time, distance traveled by light and wavelength. The
analysis takes into account that the fiber is a typical graded-index POF in which the radial distributions of light power
density and dye concentration are not uniform. The theoretical calculations agree satisfactorily with the experimental
results. The photodegradation of the ASE intensity has also been measured for both pumping schemes.

A combination of front-scattering film and directional backlight has been proposed as a system for wide-viewing-angle
transmissive liquid-crystal display (LCD). This system does not require precisely controlled phase difference film
presently used in commercial LCDs, which is expected to make LCDs simpler and less expensive. However, this system
has not, as far as we know, been put into practical use due to the blurring of images and the whitening of the scattering
film that causes the degradation of contrast.
In this article, we designed a scattering film that causes little blurring of images and whitening by optimizing conditions
of light-scattering particles added to a polymer film and addition of the dye. The blurring of images was inhibited by
doping polymer film with particles of high relative refractive index. The whitening of the scattering film was inhibited
by the addition of the dye. The film in which particles were dispersed and accumulated showed different luminance
properties and blurring of images at the same particle concentration. Finally, a directional backlight covered with the
optimized scattering film showed equivalent luminance properties to those of a commercial backlight and demonstrated
the feasibility of this system.

We investigated the effects of trans-stilbene unit in compensating birefringence in the random copolymerization method
and the anisotropic molecule dopant method. In the random copolymerization method, trans-stilbene methacrylate
(TSMA) containing the trans-stilbene unit in the side chain was polymerized with methyl methacrylate (MMA) in
solution polymerization to compensate the photoelastic birefringence and the orientational birefringence of poly(methyl
methacrylate) (PMMA). In the anisotropic molecule dopant method, trans-stilbene was added to PMMA. In the both
methods, the photoelastic birefringence and the orientational birefringence shifted from the negative side to the positive
side with an increase in the concentration of trans-stilbene unit. 0.8 mol% of TSMA almost eliminated the photoelastic
birefringence. Also, we demonstrated that poly(MMA/TSMA) exhibited no orientational birefringence with 1.9 mol% of
TSMA. 2.0 mol% of trans-stilbene almost eliminated the photoelastic birefringence of PMMA. Similarly, we
demonstrated compensating orientational birefringence with 2.0 mol% of trans-stilbene. Based on the results, the effects
of trans-stilbene unit in compensation of orientational birefringence are almost the same in the two methods. However,
in compensation of photoelastic birefringence, the trans-stilbene unit had 2.5 times higher effect in the random
copolymerization method than that in the anisotropic molecule dopant method. Photoelastic birefringence is caused in
elastic deformation below Tg, in which the side chains are mainly orientated while the polymer main chains are scarcely
orientated. Therefore, we concluded that addition of trans-stilbene unit to the side chain enhanced the effect for
compensating photoelastic birefringence.

We have succeeded in development of a simulation specialized for GI POF. In this study, we investigated the
propagation characteristics of GI POF by use of this simulation. Propagation properties of multi-mode optical fibers can
be calculated by the scalar-wave equation derived from Maxwell's equations. However, calculated impulse response
disagrees with measured results. The factors of this disagreement have been generally explained as mode coupling and
differential mode attenuation. These effects can be calculated by the power flow equation, as it has been applied for
analysis of glass optical fibers and step-index polymer optical fibers. In this study, we applied the power flow equation
to the graded-index polymer optical fiber (GI POF). The equation contains several parameters: propagation constants,
coupling coefficients, and attenuation coefficient. In order to define these parameters, we fabricated poly methyl
methacrylate (PMMA) based GI POF. Propagation constants of the GI POF were calculated by use of the finite-element
method. Coupling and attenuation coefficients were estimated based on comparisons of measurements with simulation
of differential mode attenuation and differential mode delay. We assigned these values to the power flow equation and
solved it by use of the finite difference method. As a result, bandwidth characteristics calculated by this simulation well
agreed with measurements. Moreover, it was found that the effect of mode coupling on impulse response of GI POF was
more influential than that of differential mode attenuation and that higher modes were subject to mode coupling than
lower modes and they were coupled into lower mode.

The purpose of this study is to design an optimal strontium carbonate (SrCO3) crystal which can effectively compensate
the orientational birefringence of polymers. Additionally, we try to compensate large positive birefringence which
polycarbonate (PC) exhibits. Furthermore, we analyze the orientational behaviors of the crystals in biaxially drawn
polymer films. As a result of the measurement of orientational birefringence of the polymer films doped with SrCO3 with
various average sizes and aspect ratios and estimation of orientation function of the crystals, we found out that SrCO3
with higher aspect ratio and larger size had higher compensation efficiency for the birefringence. As a result of
measurement of transparency, we found out that the copolymer film doped with SrCO3 with higher aspect ratio and
larger size was less transparent. Therefore, it was suggested that we should design an optimal crystal for particular
purposes from the standpoint of the birefringence compensation efficiency and transparency when we apply this method
to an optics application. Additionally, we succeed in designing a zero birefringent PC by doping with SrCO3.
Furthermore, we found out that SrCO3 was aligned in a perpendicular direction to the thickness direction and was
randomly oriented in planar direction in biaxially drawn polymer films.

The graded index polymer optical fiber (GI POF) has been proposed as a media for very short reach network because of
its high flexibility, low laying cost and excellent transmission characteristics. However, the plasticization efficiency
which causes by the high refractive dopant decreases the glass transition temperature (Tg) in the center of the core and
deteriorates thermal stability of fibers. In this paper, thermally stable PMMA based GI POF was successfully fabricated
for the first time by designing dopant molecule which has little plasticizer effect. Tg at the core region was improved to
104 °C while that of conventional GI POF is 86 °C. Stability of attenuation at 85 °C/dry and 75 °C/85 %RH were
clarified to be as high as that of non-doped step index POF.

Nanoparticles doped PMMA films were prepared without surface treatment agent in order to investigate particle size and
concentration dependence of orientation-inhibition effect and photoelastic coefficient reduction. It is suggested that
nanoparticles with a diameter of less than about 30 nm exhibit orientation-inhibition effect. Photoelastic coefficient
reduction was independent of particle size and proportional to volume fraction. Doping nanoparticles has an insignificant
effect on degrading the transparency of polymers if the combination of nanoparticles and polymer matrix is appropriate.

Graded-index (GRIN) progressive addition lens (PAL) was successfully fabricated, and GRIN's potential for aberration
correction of PAL was confirmed. GRIN material was prepared by partial diffusion of methyl methacrylate (MMA (nd at
polymer = 1.492)) monomer into cross-linked benzyl methacrylate (BzMA (nd at polymer=1.568)) flat gel, and GRINPAL
was prepared by polymerization of the GRIN material attached to a mold of commercially available PAL. GRIN
polymer materials have been used for various applications such as rod lenses and optical fibers. GRIN represents gradual
change of refractive index in a material, which adds or reduces light focusing power of the material. PAL is a multifocal
spectacle lens for presbyopia. However, some localized aberrations (especially astigmatism) in PAL have not yet been
reduced satisfactorily for decades by optimizing surface geometry of a lens. In this research, we propose to employ
GRIN materials for astigmatism reduction of PALs. BzMA flat gel was prepared by UV polymerization of BzMA, crosslinking
agent ethylene glycol dimethacrylate (EDMA) and photopolymerization initiator DAROCURE 1173. MMA
monomer was diffused into BzMA flat gel from a portion of periphery for several hours. The obtained GRIN material
was attached to a mold of commercially available PAL and polymerized by UV. As a result, reduction of astigmatism
was confirmed locally in the fabricated PAL and GRIN-PAL using lens meter. In conclusion, GRIN-PAL was
successfully fabricated. The validity of GRIN employment for the astigmatism reduction in PAL was demonstrated
experimentally.

Optimum combination of light source and medium (optical fiber) for radio-over-fiber application in home optical network was investigated. Japan National Television System Committee (NTSC-J) signal was employed to study the spectrum and the movie quality in different multi-mode fiber link. Noise in glass-based multi-fiber link was lowered by switching the light source from a Fabry-Perot (FP) to a vertical cavity surface-emitting laser (VCSEL). A graded-index plastic optical fiber (GIPOF) link performed a low-noise transmission using FP laser diode. The results supported the GIPOF link to be a good low-cost analog optical link solution using FP laser diode and no lens.

We demonstrate fiber optic analog transmission using NTSC-J signal. Multimode fibers with different core
diameter ranging from 9 to 500 μm were tested in terms of transmission capability under different degree of
misalignments between fibers. Graded index plastic optical fiber made of 500 μm core have shown high potential
in stable analog transmission based on effective light coupling and low modal noise impairment.

A novel fabrication method of graded index polymer optical fibers (GI-POFs) called the "co-extrusion process" is
proposed and demonstrated for first time. This continuous fabrication process can reduce the fabrication cost of GI-POFs.
Dopant diffusion temperature, dopant diffusion time, and the molecular weight of PMMA were optimized. By this
optimization, desirable refractive index profile was achieved. Therefore, it is exhibited that the GI-POF obtained by the
co-extrusion process has as high bandwidth as the one prepared by the conventional interfacial-gel polymerization process.

We have started the basic researches in order to investigate and explain the relation between photonics polymers and
their properties. And based on them, we have proposed and demonstrated photonics polymers with new optical
functions for application in photonics fields, for example, graded-index polymer optical fibers (GI-POFs), highly
scattered optical transmission polymers, zero-birefringence optical polymers, and polymer optical fiber amplifiers and
lasers. We propose the concept of "Fiber to the Display" and will apply these photonics polymers for it. In this concept,
the GI-POF is directly connected to a large and high-quality display with more than gigabit order data transmission.
Therefore, the real-time communication by high quality motion picture will become available for the first time even at
home. The gigabit technology which we propose will bring us back to "Face-to-Face Communication".

We reported the "birefringent crystal dopant method" in order to compensate the orientational birefringence of polymers for optical devices. In this method, a birefringent inorganic crystal which has rod-like shape is homogeneously doped into a polymer and it compensates the orientational birefringence of the polymer. Strontium carbonate (SrCO3) was selected for this purpose because it has a large birefringence and a rod-like shape. SrCO3 was synthesized and doped into a poly(MMA/BzMA=78/22 (wt/wt)) (78/22 polymer) film and a cycloolefin polymer film and the films were drawn above glass transition temperature (Tg). The orientational birefringence of the drawn film at a wavelength of 633 nm was compensated and reduced by doping with SrCO3. Furthermore, we analyzed the transparency and thermostability of the films.

A novel rear projection screen (Blue Ocean screen, Nitto Jyushi Kogyo, Co., Ltd.) has been developed. Blue Ocean screen is a single polymer plate requiring no lens element. The projected image is formed on the screen surface by the multiple light scattering. An image light is multiply scattered and is converted into homogeneous light distribution efficiently due to the internal particles of micron order dispersed in the acrylic polymer matrix. An ambient light is reduced by the dye molecules doped in the polymer and the anti-reflective coating on the screen surface. The condition of the particles and the concentration of the dye molecules have been optimized by the ray tracing simulation program based on Mie scattering theory using a Monte Carlo method. The screen containing the particles of optimum condition exhibits the wide viewing angle, the well-controlled color balance, and the high sharpness level at the same time. The contrast level of the projected image in ambient light is improved by controlling the concentration of the dye molecules. This paper describes the optimization obtained theoretically and experimentally, and demonstrates the advantage of Blue Ocean screen.

We have proposed the highly scattering optical transmission (HSOT) polymer, and have applied it to a high efficiency backlight for liquid crystal displays (LCDs). It is an important candidate for new various optical devices. In the present work, the multiple scattering modeling simulation has been developed. Also the effect of adjacent particles inside the HSOT polymer is demonstrated. It follows that the numerical calculation considering the effect of adjacent particles has precisely reproduced multiple scattering phenomena inside the HSOT polymer. For an application of HSOT polymer to LCD backlighting system, the optimal design of illuminating property was conducted by determining the internal particle condition

In the field of LANs, transmission systems based on a multimode silica fiber network is heading towards capacities of Gb/s. We have proposed a low-loss, high-bandwidth and large-core graded-index plastic optical fiber (GI POF) in data-com. area. We sill show that GI POF enables to virtually eliminate the “modal noise” problem cased by the medium-core silica fibers. Therefore, stable high-speed data transmission is realized by GI POF rather than silica fibers. Furthermore, advent of perfluorinated (PF) polymer based GI POF network can support higher transmission than silica fibers network because of the small material dispersion of PF polymer compared with silica. In addition, we proposed a “highly scattering optical transmission (HSOT) polymer” and applied it to a light guide plate of a liquid crystal display (LCD) backlight. The advanced HSOT polymer backlight that was proposed using the HSOT designing simulation program demonstrated approximately three times higher luminance than the conventional flat-type HSOT backlight of 14.1-inch diagonal because of the microscopic prism structures at the bottom of the advanced HSOT light guide plate. The HSOT polymer containing the optimized heterogeneous structures produced homogeneous scattered light with forward directivity and sufficient color uniformity.

We have developed a highly scattering optical transmission (HSOT) polymer, and have succeeded in applying it to a highly efficient backlight in liquid crystal displays (LCDs). In the present work, a multiple scattering modeling simulation has been developed. Also the effects of adjacent particles inside the HSOT polymer are demonstrated. Although Mie scattering theory is based on the assumption that there exists one particle, light scattering intensity profiles are extended by adjacent particles in measurement data. In order to improve the multiple scattering modeling simulation, light scattering intensity profiles calculated by Mie scattering theory are modified by using the experimental correction function. It follows that the numerical calculation improved by taking account of the adjacent particles has precisely reproduced multiple scattering phenomena inside the HSOT polymer. Based upon the results of multiple scattering analysis, an optimal design has been developed and applied to an LCD backlight system. By altering the internal particle condition, uniformity of color and brightness on the top face of the backlight can has been achieved

Absorption spectra of lanthanideions in perfluorinated (PF) plastic solution were measured, and the radiative properties were determined by the absorption measurements and the Judd- Ofelt theory. Fluorescence spectrum of Nd3+ in PF plastic solution from 900 nm to 1350 nm, pumped at 580 nm, were measured for the first time. Lasing properties of a rhodamine 6G-doped graded-index plastic optical fiber laser (GI-POFL) and a rod laser were investigated. All measurements demonstrated the superior performance of the GI-POFL. This paper also discusses the lasing properties on the basis of near-field pattern measurements.

Optical polymers which exhibit no birefringence with any orientation of polymer chains are desirable to realize high performance optical devices that handle polarized light. We defined such polymers as 'zero-birefringence polymer' and demonstrated two methods for synthesizing the zero- birefringence polymers: the random copolymerization method and the anisotropic molecule dopant method. Orientational birefringence is compensated by random copolymerization using a positive and a negative birefringence monomers at specified ratio in the random copolymerization method. Poly(methyl methacrylate-co-benzyl methacrylate) synthesized by this method showed no orientational birefringence with any orientation degree. In the anisotropic molecule dopant method, orientational birefringence of polymers is compensated by doping with 3 wt percent of trans-stilbene as the anisotropic molecule. Furthermore, we demonstrated the isotropic particle dopant method to reduce orientational birefringence of polymers. Orientation birefringence for polymethyl methacrylate film was decreased by approximately 20 percent by doping with 2 wt percent of silica particle with an average diameter of 7 nm as the isotropic particle dopant.

We report on the lasing action of the graded-index polymer optical fibers containing dyes, such as Rhodamine B, Rhodamine 6G, Perylene Orange, and Pyrromethene 567. These dyes have been incorporated into poly(methyl methacrylate- co-2-hydroxythyl methacrylate). These fibers were transversely pumped at 532 nm with a frequency-doubled Q- switched Nd:YAG laser. Slope efficiency of 24 percent and output of 1.2 mJ were obtained with a Rhodamine 6G-doped fiber. A lifetime of 200,000 pulses at 10 Hz was achieved with a Rhodamine B-doped fiber. GI POF containing a Nd- chelate have also been fabricated. The absorption spectrum of the fiber exhbit3ed several strong bands in the visible and IR regions. We have observed IR fluorescence of the Nd3+ ion of the fiber at room temperature when it was pumped with an Ar+-pumped dye laser at 580 nm. The Judd-Ofelt theory was applied to the absorption spectrum of Nd3+ in polymer to determine the Judd-Ofelt parameters. From the theory, various radiative properties, such as transition probability, branching ratio, and emission cross section for various emission levels, have been determined and reported.

We encapsulated rare earth ions such as europium and neodymium with organic ligands to incorporate them into polymer matrices. Their spectroscopic properties in polymer hosts and organic solutions were studied. Infrared emission has been observed from a neodymium-doped perdeuterated core graded index polymer optical fiber.

We proposed highly scattering optical transmission (HSOT) polymers and applied it to a light pipe of a backlighting system for liquid crystal displays (LCDs). The HSOT polymer backlighting system having not only approximately twice the brightness but also twice the efficiency of the conventional one was realized based on analysis of multiple scattering in the HSOT polymers. The problem of color dispersion which had been believed to be the nature of scattering phenomenon was solved by optimizing the heterogeneous structures in the HSOT polymers. As a result, the HSOT polymer backlighting system with sufficient color uniformity was achieved. In addition, the HSOT polymer backlighting system was composed of fewer parts than those of the conventional transparent one. The HSOT polymer backlighting system is suitable for recent thin LCDs because of these advantages.

Recent status of the polymer optical fiber (POF) for high speed data communication and telecommunication is reviewed. The GI POF was proposed for the first time at Keio University, and several methodologies to fabricate GI POF have been currently proposed. In this paper, we clarify the great advantage of perfluorinated (PF) polymer as the polymer matrix of low-loss and high bandwidth graded-index (GI) POF. It is generally known that the PF polymer can decrease the intrinsic absorption loss compared with poly methyl methacrylate (PMMA), which is the conventional material of POF. Furthermore, it was found that low material dispersion of the PF polymer is another advantage to obtained the high bandwidth GI POF. It was clarified for the first time that the power distribution of modes formed by the mode dependent attenuation was the dominant factors of the higher bandwidth of the GI POF than theoretically predicted bandwidth, while the effect of the mode coupling was small.

Recent status of the polymer optical fiber (POF) for high speed data communication and telecommunication is reviewed. The GI POF was proposed for the first time at Keio University, and several methodologies to fabricate GI POF have been currently proposed. In this paper, we clarify the great advantage of perfluorinated (PF) polymer can decrease the intrinsic absorption loss compared with poly methyl methacrylate (PMMA), which is the conventional material of POF. Furthermore, it was found that low material dispersion of the PF polymer is another advantage to obtain the high bandwidth GI POF. It was clarified for the first time that the power distribution of modes formed by the mode dependent attenuation was the dominant factors of the higher bandwidth of the GI POF than theoretically predicted bandwidth, while the effect of the mode coupling was small.

Recent progress of the graded-index polymer optical fiber (GI POF) and polymer optical fiber amplifier (POFA) are reviewed. Because the low attenuation of light transmission in the perfluorinated (PF) polymer base GI POF enables 500 to 1000 m transmission, more accurate analysis is required in the refractive index profile to realize the order of giga bit transmission. Furthermore, recent improvement of the thermal stability of the GI POF is introduced. We clarified that the stability of the refractive index profile and the attenuation under high temperature and high humidity atmosphere can be improved by selecting the suitable dopant material. We demonstrated that organic dye-doped POFA cover a wide spectral range in the visible with a best observed gain of 37 dB in a Rhodamine B-doped POFA pumped at 550 nm. Also, wit a GI POF doped with europium chelate of hexafluoroacetylacetone in tris form, we observed superfluorescence, evidenced by spectral narrowing and lifetime shortening. The prospect is that the wide choice of organic dyes and rare earth chelates offers optical amplifiers and superfluorescence sources for a variety of communication and sensor applications.

Recent progress of the graded-index polymer optical fiber (GI POF) is reviewed. Because the low attenuation of light transmission in the perfluorinated (PF) polymer base GI POF enables 500 to 1000 m transmission, more accurate analysis is required in the refractive index profile to realize the order of giga bit transmission. The analytical procedure of the bandwidth characteristics of the GI POF is described in this paper. Furthermore, recent improvement of the thermal stability of the GI POF is introduced. We clarified that the stability of the refractive index profile and the attenuation under high temperature and high humidity atmosphere can be improved by selecting the suitable dopant material.

Organic dyes and rare earth chelates have been chosen and incorporated into the core regions of graded index (GI) polymer optical fibers (POF) as gain media. Since the synthetic polymer shows much better compatibility with organic fluorescent materials and is amenable to high active dopant concentrations, the doped POFs produce high gains in short lengths of fiber. We demonstrated that organic dye-doped polymer optical fiber amplifiers (POFA) cover a wide spectral range in the visible with a best observed gain of 37 dB in a Rhodamine B-doped POFA pumped at 550 nm. Also, with a GI POF doped with europium chelate of hexafluoroacetylacetone in tris form, we observed superfluorescence, evidenced by spectral narrowing and lifetime shortening. The prospect is that the wide choice of organic dyes and rare earth chelates offers optical amplifiers and superfluorescent sources for a variety of communication and sensor applications.

We have proposed a highly scattering optical transmission (HSOT) polymer for use as a high luminance light source medium. This polymer contains specified internal microscopic heterogeneous structures for controlling light scattering properties. A LCD backlight using the HSOT polymer has twice the brightness of the conventional transparent PMMA-based backlight because of multiple scattering phenomenon inside the HSOT polymer. In this paper, such a light scattering phenomenon was quantitatively analyzed by a ray tracing based on Mie scattering and Monte Carlo simulations. Subsequently, we proposed the new HSOT backlight system having higher luminance and uniformity of white color illumination.

Improvement of the optical fiber oxygen sensor based on the fluorescence quenching by oxygen gas was studied. Using the newly synthesized poly-l-methylmethacrylate (PMtMA) and its blend of the PMtMA/PMP as the cladding layer, in which sensing dye was doped, the plastic optical fiber (POF) O2 sensor with high sensitivity and a fast response time could be realized. In addition this sensor didn't receive any affect by humidity.

A novel TE-TM mode converter using optically active polymers (OAPs), which can be fabricated much more easily than the conventional ones, was proposed. To achieve its phase- matched operation, two methods for controlling birefringence in the OAP waveguides were studied and hence TEo-TMo mode conversion with a high efficiency of about 70 percent was obtained for the first time.

Amplification characteristics of graded-index (GI) type organic dye doped polymer optical fiber amplifiers (POFAs) are discussed. As an organic dye for optical amplification, Rhodamine 6G, Rhodamine B, and Perylene Red are doped in the core region of polymer optical fibers (POFs). These POFA can obtain optical gain in the visible region of wavelength from 570 nm to 620 nm. POFA is promising for extraordinary high power optical amplification in comparison with rare-earth ions doped silica fiber amplifier. For example, output power of 1 kW with a gain of 30 dB can be obtained by using a Rhodamine B doped POFA at a low dye concentration of 1 ppm. Additionally, a novel solid-state POFA amplifier system is demonstrated.

An organic dye (Rhodamine B) doped polymer optical fiber amplifier (POFA) of the graded- index (GI) type was successfully prepared for the first time. The GI-POFA of only 500 mm in length gave 27 dB in gain at 591 nm of signal wavelength. Additionally, absorption cross section and emission cross section of Rhodamine B in PMMA matrix were estimated, which were required to analyze amplification mechanism in the POFA.

A high-bandwidth graded-index (GI) polymer optical fiber (POF) was successfully obtained by a new random copolymerization technique. The bandwidth of the GI POF is about 1 GHz (DOT) km, which is 200 times larger than that of the conventional step-index (SI) POF. The total attenuation of the transmission is 150 - 200 dB/km at 652 nm wavelength and the tensile strength is about 1600 kg/cm2.

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Journal of Applied Remote SensingJournal of Astronomical Telescopes Instruments and SystemsJournal of Biomedical OpticsJournal of Electronic ImagingJournal of Medical ImagingJournal of Micro/Nanolithography, MEMS, and MOEMSJournal of NanophotonicsJournal of Photonics for EnergyNeurophotonicsOptical EngineeringSPIE Reviews